While authorities cannot confirm if two storms brewing in the region will become a “double typhoon”, Hong Kong weather officials expect unstable conditions with squally showers and thunderstorms over the city in the coming days.

After sweltering under a heatwave stretching more than two weeks, Hongkongers can expect a rainy and windy week ahead as the first of two storms nearing the southern China coast will drop temperatures to as low as 26 degrees Celsius (78.8 degrees Fahrenheit), according to the Observatory.

As of noon on Sunday, a tropical depression over the southern part of the South China Sea was centred about 350km south-southwest of Xisha, or Paracel Islands. It was expected to come within 800km of Hong Kong at about noon on Monday.

The typhoon signal No 1 might be issued but Observatory senior scientific officer Cheng Yuen-chung said it was still too early to confirm.